Chapter 11 – From Hominoid to Hominin.docx

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School

McMaster University

Department

Biology

Course

BIOLOGY 1M03

Professor

Jurek Kolasa

Semester

Fall

Description

Chapter 11 – From Hominoid to Hominin
• Homininae ­ clade containing gorillas, chimps and humans
• Hominina – clade containing humans, our relatives
• Characteristics of humans include:
o Bipedalism
o Differences in dental anatomy from apes
o Large brains relative to body size
o Long period of juvenile development
o Dependence on a material and symbolic culture
• Genetic data indicates that the last common ancestor of humans and chimpanzees lived between 7
and 5 mya
o Ardipithecus – related more closely to chimpanzees than modern humans
o Orrorin tugenensis – related closer to chimpanzees; arm and finger bones show
adaptations for climbing
o Sahelanthropus tchadensis – earliest known hominin living around 7­6 mya; hadboth
derived and ancestral traits; relatively flat face and massive browridge over the eyes
• Hominin species living in Africa between 4 and 2 mya were divided into three genera:
Australopithecus
• A. anamensis – existed between 4.2 to 3.8 mya,
o Was bipedal but skull was apelike
o Large molars and small canines mark it as a hominin
• A. farensis – existed from 4 to 3 mya and is the best known Australo. species
o The skull and dentation are human and apelike
o Human­looking knees, hip joints and Laetoli footprints indicate bipedalism
o Exhibited sexual dimorphism
o Most likely slept in trees like most other primates
• A. africanus – existed from 3 to 2.2 mya; includes the Taung child skull
o Postcranial anatomy indicated it was bipedal
o Has more derived traits including dental differences and juveniles which mature quickly
o